A nozzle comprised of a thin, flexible membrane material having a plurality of pores is disclosed. In one embodiment, the pores have an unflexed exit aperture diameter in the range of about 0.5 to about 2 microns (preferably about 1 micron) and are positioned substantially uniformly in the material, preferably about 50 microns apart. The nozzle preferably has a conical or trumpet-shaped cross-section. In another aspect of the invention, the exit aperture of the nozzle is surrounded by an elevated area protruding above the substantially planar exit side of the membrane in order to prevent intrusion of liquid back into the nozzle. The nozzle can be used to form an aerosol containing a pharmaceutical composition from the exit side of the nozzle upon forcible application of the composition to the entrance side of the nozzle. This aerosol can be used to administer the pharmaceutical composition, for example, to the eye or to a selected portion of the respiratory tract. The nozzle is preferably a component of a container which holds a formulation of drug.